Non-invasive method for measuring a physiological parameter via a confocal spectroscopic measurement device

Abstract

The present invention relates to a method for measuring a physiological parameter of a subject by means of an optical measurement device, said method comprising the steps of: setting into place the optical measurement device ( 1, 1 bis ) facing a skin surface ( 10 ) of the subject, so that the object focal spot of the optical objective is positioned at a predetermined skin depth, receiving by the photosensitive receiver ( 4 ) light rays from the first object focal spot, at the predetermined skin depth, analyzing the light rays received by the photosensitive receiver ( 4 ), and comparing the results of the analysis with known data, so as to determine the physiological parameter of the subject.

The invention claimed is: 
     
       1. A method for measuring the skin bilirubin level of a subject which is applied by an optical measurement device comprising:
 an optical objective positioned at an optical axis, 
 at least three sources of light each emitting radiations with different wavelengths comprised between 400 and 800 nm, 
 a first pinhole positioned on a first plane and centered on a first image focal spot of the optical objective so as to only let through light rays from a first object focal spot of the optical objective, 
 a second pinhole positioned on a second plane and centered on a second object focal spot of the optical objective so as to let through light rays emitted by the at least three light sources from only the second object focal spot, 
 a photosensitive receiver adapted to receive the light rays from the first image focal spot downstream from the first pinhole, 
 a semi-reflective planar mirror, said mirror being configured for transmitting the light rays emitted by the at least three light sources towards the optical objective, and for transmitting the light rays from the first object focal spot towards the photosensitive receiver, 
 a first polarizing plate positioned between the first pinhole and the semi-reflective mirror and a second polarizing plate positioned between the second pinhole and the semi-reflective mirror, wherein polarization axes of the first polarizing plate and the second polarizing plate are perpendicular, 
 said method comprising the steps of:
 setting into place the optical measurement device facing a skin surface of the subject, so that the first object focal spot of the optical objective is positioned at a predetermined skin depth, 
 emitting light rays by the at least three light sources towards a second image focal spot of the optical objective, at the predetermined skin depth, 
 receiving by the photosensitive receiver light rays emitted by the at least three light sources, reflected by the skin and from the first object focal spot, at the predetermined skin depth, 
 measuring an absorption level by the skin of the light rays emitted by the at least three light sources from an analysis of the light rays received by the photosensitive receiver, and 
 determining said skin bilirubin level of the subject from comparing the measured absorption level with known data. 
 
 
     
     
       2. The method according to  claim 1 , wherein the predetermined skin depth is greater than 1 mm.